[Two novel potential markers for iron metabolism: hepcidin and non-transferrin-bound iron (NTBI)]

Iron is an essential metal for all living organisms. For example, iron is used in hemoglobin synthesis. However, iron overload can cause serious organ damage. Therefore, iron balance is tightly regulated while iron dynamically moves throughout the body, including the gastrointestinal tract, bone marrow, blood, liver, and spleen. Iron balance occasionally collapses, allowing either iron deficiency or iron overload to occur. Various laboratory tests and serum markers are now available for evaluating such iron dysregulation. The hepatic iron concentration, as determined by liver biopsy, and serum ferritin are both quite informative. In addition, certain novel markers and modalities are becoming available due to remarkable progress made in recent research on iron metabolism. In this review, the iron regulatory peptide-hormone hepcidin and non-transferrin-bound iron (NTBI) are introduced as novel potential biomarkers for iron metabolism.